First-order logic - Wikipedia, the free encyclopedia

First-order logic (FOL) is a formal deductive system used in mathematics, philosophy, linguistics, and computer science. It goes by many names, including: first-order predicate calculus (FOPC), the lower predicate calculus, the language of first-order logic or predicate logic. Unlike natural languages such as English, FOL uses a wholly unambiguous formal language interpreted by mathematical structures. FOL is a system of deduction that extends propositional logic by allowing quantification over individuals of a given domain of discourse. For example, it can be stated in FOL "Every individual has the property P".